Excursion ac struggle
Hi i do not know hat to do ...
I replaced nearly every component on my truck's ac system
I tried moore and less freon as well as different orifice tubes
New kondenser new compressor new accumulator front and rear orifice tubes / the valve block in the rear...
New viscous fan clutch ...
And the ac still blows warm air ....compressor is engaged nearly 24/7 and the freon return line gets warm too
pressures seem to be okay on the high side and bit too high on the low side if I get in to stop and go traffic I just wand to leave the truck... oh and the front and rear do the exat same
maybe someone has an idea ?

Sorry for my bad Englisch and greetings from germany

 

Moved to this forum.

 

the AC system must be fully evacuated, pull a Vacuum on it and hold it for a minimum of 30 minutes, I prefer an hour or more to check for leaks....

if the compressor has been changed, it is very likely there is too much PAG oil in the system, get a Flush Kit, and a few bottles of 91%-99% isopropyl alcohol and flush that thru the entire system with high pressure air., if a Rear AC is involved, there is an Orifice back there, change it out.

the Dryer and front orifice must be changed, but I think it is a T*** valve, forget the term.

you must verify that the correct amount of Freon is install, and the correct ounces of PAG oil, both should be on the label over the radiator, or in the shop manual.

 

i thought I had a picture of the rear orifice, it is below the floor of the truck,



https://www.thedieselstop.com/thread...-amount.60228/



a listing of Freon amounts for all Ford vehicles.

https://ricksfreeautorepairadvice.co...rant-oil-type/

Ford EXCURSION Refrigerant Capacity and Refrigerant Oil Type

2005-01 All Eng.; w/o Rear AC – 42.00 Oz. R-134a; 9.00 Oz. PAG-46


All Eng.; w/ Rear AC – 68.00 Oz. R-134a; 14.00 Oz. PAG-46

5 of the 12oz cans plus ½ of the 6th can.

This will 2oz short of the stated 68 oz… must better to be slightly low, rather than too much,

even 1 oz over-charge and the efficiency goes downhill fast.


2000 All Eng.; w/o Rear AC – 40.00 Oz. R-134a; 9.00 Oz. PAG-46


All Eng.; w/ Rear AC – 68.00 Oz. R-134a; 14.00 Oz. PAG-46

https://fanovo.com/industry-release/...r134a-can-tap/

 

note the very last item, that is the Rear Expansion Valve,
this pix is from Rock Auto

here is more info:
There are 3 of them.

You Tube

 

Just had mine done, I hope you didn't miss the H-block (A/C expansion valve).

If someone ran sealant into the system and it wasn't flushed and both front and rear orifice tubes were not replaced, you're going nowhere fast.

Did you check the A/C clutch depth with a feeler gauge also?

 

The system was evacuatet and refilled professionaly in a shop by myself
i even tried like 2-4-6 oz less freon Front orifice tube and rear "H" block changed multiple times at this point there both oem Motorcraft parts from Rockauto as well as the condenser and the accumulator the compressor is a 4season with new cluch and everythig i filled the pag oil as per spec so that schoud be fine
i checked the evap coils front and rear as well as cleaning them good inside with alcohol outside flushed with water and soap the blend doors work kompletley fine the hot water block off valve in the front is working fine on max ac both coolant lines to the heater core are cold.
my problem is that somehow the vent temperature and the freon return´s does not get real cold and from stock system to all what i have done it is all the same even the little stuff like the heatshield around the hvac thing in the engine bay is okay

(after driving on the highway for a pretty long time like 20-30 min the ac gets somewhat cooler)
i thing i have a pretty special problem with my ac system like i myself cant figure it out and other colleagues and workshops fail too...


that brings me to a simple question : is the AC in the Excursion up to the task or is it simply not that effective like what are youre ambient temps and vent temps
on a 90°f day i get vent temps like 60°f after like 20 min highway (front and rear pretty much the same)

 

These A/C systems are oversized, and work very well when all components are in good shape.
The first thing to check is the A/C clutch gap, see service manual pic for the 6.8.
Another thing to check would be the high and low pressures as observed by a manifold gauge set.

 

the clutch gap is fine the compressor turns fine without any abnormal noises
High side 175 psi
Low side 42 psi

at idle on a 75°f ambient temp day condenser in the shade ac on max

for my understanding the high side is fine the low is a bit high

 

Sounds like good pressures for an idle state, did you charge with R134A, or did you use a drop-in that mimics the R134A?
I'd be sure that you have the correct orifice/strainer in the front too. I believe it's the red part# F5UZ19D990AB.....

 

This really interests me S I feel like I’ve gone through the same processes as you, with similar poor performance. The only components I did not replace for the hoses and tubes. I just made repairs at an AC shop where needed. All my parts are UAC or 4S.

Some things that seem to influence are as follows:
1. Air conditioner works better when rear AC is on.
2. Engine idling with the car standing still is the worst performance, especially with the rear AC off.
3. System calls better when on recirculate and if the air is less humid to start.

I have a new blend door actuator, and all the foam is in good shape. Including the rear foams.

I questioned these parts of my install:
1. Pulley size of new compressor, was larger, and needed a longer belt. (I have an F250-sourced 6.0 in my Ex)
2. Would a high temperature orifice tube work better? The kids always complain about being cold in the back so it seems like the expansion valve side is working well.
3. Is the corrosion resistant/painted condenser coil impacting performance?

I have not tried to check this yet, but I was watching some videos about superheat and subcooling. When these numbers are off from what they should be, it can lead to things like not enough vapor or liquid making it to the compressor affecting overall performance. This kind of makes sense when you consider it works better with the rear AC on.

 

Step 1 before you do anything else. Clean, clean, clean. Dirt/material on the condensor and the evaporator will mess up heat transfer and kill efficiency. It's extremely easy for both to get dirty on the inner fin surfaces and visually look clean. High pressure water will do a decent job. HVAC cleaning foam may be needed if they're really dirty. it gets into the tight spaces and expands pushing dirt/grime out. the FRONT evaporator is behind the blower motor on passenger side of the firewall. easily accessible with only 3 small bolts. After 20yrs you'd be amazed at the accumulation of stuff these tend to collect. It's a direct shot for outside air and does a great job filtering dirt.

do you have an Excursion 6.0 compressor installed? or a Superduty specific 6.0 compressor installed? I don't know what the difference is, but they do have different compressors. If Superduty, I'm curious if that compressor has same pressure/flowrate abilities as the Excursion. The Superduty doesn't need to supply 2 zones of freon, so I could see it having lower specifications.
for the questions
1. A larger pulley will result in the compressor spinning slower than the original unit/pulley did. compressor output won't be as high as normal. shouldn't affect overall performance except when low rpm/idle. odd situation though since it's an OEM part for same motor, but potentially wrong application
2. no idea. orifice is typically used to control flowrate and to some small extent pressure. I'd stick to whatever the OEM part Ford calls for. They tuned the system for a specific heat balance
3. 100% the paint will affect heat transfer. It's another thermal layer that must be overcome for the freon to be condensed. under normal driving conditions (while moving) this won't be a big deal as air is forced across it. it will really show the effect in low airflow conditions (idle/parked) as there is less air flow across the fins. I'd recommend cleaning this off as best you can. Probably not going to be able to though without damaging the condensor

 

FYI: the replacement condensers are painted black from Ford anyway.
Probably want to refer to it as a low temp orifice tube, which would be a larger diameter metering orifice to saturate the evaporator more and quicker, but can possibly flood the coil with too much refrigerant too, I tried the green one, and i pulled it back out. Yes the factory orifice properly meters the refrigerant to the front evap as designed and should be the only one used.
The reason for the TXV (thermal expansion valve) in the rear, allows the rear system (evap) to essentially shut down once the fan is turned off. When the temp/pressure drops low enough the valve shuts down, if not and refrigerant is allowed to flow without the fan, the coil will eventually freeze over, and prevent airflow till it has been thawed. Ford use to use a suction throttling valve in the front on various R12 systems back in the late 70's and so on, This was a very efficient method, and worked very well at metering the flow of Freon based on cooling demand. The front orifice does not do this. But then again, the front is an oversized coil, and can make the cut if all is good.
To the original author, it sounds like he's replaced all but the front evap and should be working based on the work done. Without seeing the system in person, I can't really offer any other help.

 

Hi thanks for the many reply´s sounds like im not the only one with the "schuld be fine but isnt problem"
my Front condenser is new and without paint... so thats not your problem
both front and rear evap coils are cleaned spotless (I have taken them out to clean them...)
i even cleaned the little filter in the liquid line to the rear evap coil.
yesterday i felt the ac lines in the engine bay ant noticed that the liquid line from the condenser was luke warm but as it arrived at the front evap coil where the front orifice lives the line got hot again
what brings my attention to engine bay temps / Heat shields are there any like heatshields on the exhaust manifolds?
for now i tried to wrap the return lines and the liquid line from the condenser to the orifice in aluminum foil
so far it seems to be a improvement but i have to wait till it gets hot again...

maybe our problem is that the freon is not cold enough to beginn with at the expansion / Orifice tube
what would that be called superheat or subcool problems?

this was also questioned the freon is the "original" r134a not any aftermarket thing .

note:
the different size compressors.
there is not a really noticeable difference when standing still in like idle or at like 3k rpm
what the pumped amount of freon changes

 

Well, time to find the nearest ferry, and head for the US mainland....